(1) Field of the Invention
The invention relates to a fabrication method of a trenched power semiconductor structure. More particularly, the invention relates to a fabrication method of a trenched power semiconductor structure with a low gate charge.
(2) Description of the Prior Art
Compared with the conventional planar power semiconductor structure, a conducting current flows along a direction parallel with the surface of the substrate. A trenched power semiconductor structure changes the position of the gate channel by setting the gate in the trench, such that the conducting current flows along a direction perpendicular to the substrate. Therefore, the trenched power semiconductor structure can be reduced the scale of components, and raised the integration of the components. Common power semiconductors include metal-oxide-semiconductor field-effect transistor (MOSFET), and insulated gate bipolar transistor (IGBT), etc.
The main power loss of the power semiconductor includes the conducting loss due to on-resistance, and the switching loss due to the gate charge. As the operating frequency being raised, the ratio of the switching loss is more increased. For the structure characteristic of the power semiconductor, it is useful to improve the switching rate and decrease the switching loss through decreasing the gate-drain capacitor Cgd.
Therefore, to search a fabrication method of power semiconductor structure for reducing gate-drain capacitor is an important issue in this technical field.